1. Field of the Invention
The present invention relates to: a communication method in which a plurality of communication apparatuses and a repeating apparatus for relaying communication among these communication apparatuses are employed, while one communication apparatus having acquired transmission right performs multi-address calling (point-to-multipoint communication) of output data to the other communication apparatuses, and while each communication apparatus having received the output data executes output processing on the basis of the received output data; a communication system employing such communication method; and a repeating apparatus and a communication apparatus employed in such communication system. Further, the present invention relates to a computer program product for implementing each of the repeating apparatus and the communication apparatus described above. In particular, the present invention relates to a communication method, a communication system, a repeating apparatus, a communication apparatus, and a computer program product applicable to a PoC (Push-to-Talk over Cellular) service in which the technique of IP (Internet Protocol) telephone is utilized as that of transceivers so that a packet containing voice data is transmitted to a plurality of apparatuses by multi-address calling.
2. Description of Related Art
Recently, the use of real-time applications such as VoIP (Voice over Internet Protocol), VoPN (Voice over Packet Network), streaming, and the like is increasing in which voice data and video data are transmitted and received between apparatuses via a communication network such as an IP (Internet Protocol) network. Thus, IP telephone serving as an example is spreading rapidly. In the IP telephone, packeted voice data is transmitted and received via an IP network so that telephone call is realized between an apparatus on the packet transmitting side and an apparatus on the packet receiving side.
Further, attention is focused on a PoC (Push-to-Talk over Cellular) service in which the technique of IP (Internet Protocol) telephone is utilized as that of transceivers so that a packet containing voice data is transmitted to a plurality of apparatuses by multi-address calling. As a feature of the PoC service, half duplex communication is adopted in which one apparatus among a plurality of the apparatuses acquires speaking right for transmitting voice data and then this one apparatus having acquired transmission right performs multi-address calling of voice data to a plurality of the other apparatuses. This permits simultaneous communication among three or more apparatuses. Here, at the time of transmission of the voice data, which apparatus (user) has presently the speaking right is notified to each apparatus. This allows all members to recognize who is providing the speech outputted on the basis of the voice data.
Here, a communication system employing half duplex communication in which one apparatus among a plurality of apparatuses acquires transmission right (speaking right) capable of transmitting voice data and then the one apparatus having acquired transmission right performs multi-address calling of voice data to a plurality of the other apparatuses has been proposed as an electronic conferencing system in addition to the PoC service system described above (see Japanese Patent Application Laid-Open No. 6-266632 (1994)).
In such a system like the PoC service system, the electronic conferencing system, and the like that realizes one-to-a-plurality conversation by means of multi-address calling of voice data from one apparatus having acquired speaking right to a plurality of the other apparatuses, time, effort, and cost are reduced that is necessary for transmitting the same contents to each person. Further, even in a case that a speech is intrinsically directed to one specific person, when a speaking person having acquired speaking right transmits the contents also to the other persons by multi-address calling, the information is shared among all the members including the persons other than the intrinsic target person of speech. This is another advantage.
Nevertheless, in a conventional system such as the PoC service system, the electronic conferencing system, and the like, which apparatus (user) has presently the speaking right is notified, but to whom the speech is directed, that is, the target person of speech, is not identified. This has caused a fear that the target person of speech may fail to listen to the speech. On the contrary, in order that the fear of failing to listen should be avoided reliably, each user need listen to all speeches carefully even for speeches not important for the specific user. This has caused a problem of time and effort.